Cinematographic annual : 1931 (1931)

Record Details:

Title:
Cinematographic annual : 1931
Date:
1931
Publisher:
Hollywood : The American Society of Cinematographers, Inc.
Volume:
Cinematographic annual : 1931
Leaf #:
000160
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
{"Media History Digital Library","Richard Koszarski","Jeff Joseph"}
Coordinator:
Media History Digital Library
Description:
Date Added:
March 21, 2024
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128 CINEMATOGRAPHIC ANNUAL It should be noted that above a certain current for each size carbon there is practically no increase in the intrinsic brilliancy of the central part of the crater — merely an increase in crater size and intrinsic brilliancy near the edges of the crater. It is also evident that after this critical current has been reached the intrinsic brilliancy is the same for the central position of the crater on a 10 mm. carbon as for the 13 mm. carbon. This important characteristic will be referred to later in relation to the optical system. The approximate current at which the central portion of the crater reaches its maximum is the minimum recommended current in Table I. The candle-power of the crater from a point directly in front is shown in Fig. 2 for various values of arc current. Of more importance for projection than the candle-power directly in front of the crater, however, is the light distribution about the crater. Polar candle-power curves for two currents are given in Fig. 3. 90' 80" 70* 60 *12 MM. CARBONS 30 AMPS 14 MM. CARBONS 47 AMPS. S.RA. POSITIVE CARBONS CANDLE POWER \ DISTRIBUTION : \ R2-99 30* 40 90* 80° 70' 60 50' Fig. 3. Polar candle-power curves showing light distribution about the crater.